What is the ai_session cookie?
ai_session is an HTTP cookie set by the JavaScript SDK of Azure Application Insights, the application performance monitoring component of Microsoft's Azure cloud platform. It's used by websites and web apps that have integrated Application Insights to measure performance, errors, and user behavior.
The cookie typically appears as soon as the Application Insights SDK loads on the page, regardless of whether the visitor actively interacts with the site, since the monitoring script runs automatically on page load.
What data it stores
ai_session stores an automatically generated session identifier used to link together requests, page views, and events recorded by Application Insights within the same visit. The exact value and internal format may vary depending on the SDK version used.
Data collected through this cookie is sent to Microsoft's Azure Application Insights infrastructure, where it's aggregated into telemetry reports (performance, errors, traffic) for the site or application owner.
What it is used for
The cookie's purpose is strictly technical/analytical: it allows Application Insights to reconstruct a user session (a sequence of actions within a limited time window) to calculate metrics such as session duration, number of pages visited, or error rates.
For the site administrator, this data helps identify performance issues, debug errors, and understand how users interact with the application.
Does it require consent?
CookieFix classifies ai_session under statistics (analytics). Since it's used for monitoring and analyzing visitor behavior, it does not fall under the "strictly necessary" exemption in Article 5(3) of the ePrivacy Directive (in Romania, transposed via Law 506/2004).
- The site administrator must obtain the visitor's explicit consent before the Application Insights script loads and the cookie is set.
- The cookie must be listed in the site's cookie policy, including the provider (Microsoft Azure), purpose, and duration.
- Refusing consent must not block access to the site's content.
How to block or delete ai_session
A visitor can manually delete or block ai_session from browser settings (Chrome, Firefox, Edge, Safari), under the cookie and site data management section, or by using private/incognito browsing.
For site administrators, the most practical solution is using a CMP (Consent Management Platform) like CookieFix, which automatically blocks the Application Insights script from loading until the visitor consents to the statistics category, preventing the cookie from being set prematurely.
Frequently asked questions
It doesn't contain directly identifiable personal data like a name or email, just a technical session identifier. However, combined with other telemetry data, it can contribute to behavioral profiling, which is why it's treated as an analytics cookie.
It typically lasts about 30 minutes, resetting with each new interaction and expiring automatically after a period of inactivity.
No. Application Insights usually sets two cookies: ai_session (identifies the current session, expires after 30 minutes) and ai_user (identifies the visitor long-term, with a much longer duration).
Yes, if the cookie is set in the end visitor's browser and used for traffic/behavior analysis, ePrivacy/GDPR rules apply regardless of whether the results are used only internally by developers.